If you want some kind of justification, I suppose you could say some poetic bullshit about the beauty of the MadonnaEarthMother in a twilight state of base biological unity with her child-satellite of dependence.
Or blame it on your roommate.

But hey, she's a women. Women get freaked out even by simple tasteful nudes.
At least she didn't discover your hardcore magazine with pictures of her sister pasted over the model's faces.